Published work from our laboratory shows that adipose tissue inflammation is a key pathological process linked to metabolic stress and vascular endothelial dysfunction in obese subjects, supporting the growing paradigm that both quality and quantity of fat are germane to systemic disease processes. Our preliminary data demonstrate that impaired angiogenic and vasodilator functions of the adipose microvasculature are closely linked to proinflammatory and hypoxic adipose phenotypes. As adipocytokines released from fat alter vascular mitochondrial function in a manner that increases reactive oxygen species (ROS) and impairs endothelial nitric oxide bioaction, we will examine the importance of inflammation and mitochondrial dysfunction as interrelated mechanisms linked to impaired adipose vascular profiles. In aim 1, in 150 obese individuals we will biopsy fat depots during bariatric surgery and characterize the relation between adipose inflammation and depot-specific angiogenic capacity and vascularity in relation to clinical phenotypes. We hypothesize that adipose inflammation will be associated with capillary rarefaction and impaired angiogenesis. In aim 2, we will isolate endothelial cells from the adipose tissue of each subject from aim 1 and characterize mitochondrial morphology, ROS production, and gene expression using fluorescence imaging and quantitative PCR. We will complement these analyses by studying vasodilation of adipose microvessels by videomicroscopy in response to mitochondrial modulators. We hypothesize that mitochondrial dysfunction will be linked to impaired endothelium-dependent vasodilation and angiogenesis. In aim 3, we will study the effects of extensive weight loss following bariatric surgery by repeating the adipose and vascular studies described in aims 1 and 2, at 1- and 12-months after bariatric surgery in the same 150 subjects. We will seek to identify metabolic, mitochondrial, and/or inflammatory determinants of endothelium-specific functions within fat in association with both early and late stages of weight decrease. The proposed studies are positioned to yield novel information about mechanisms of obesity- induced cardiometabolic disease and the effects of bariatric weight loss on vascular biology in a group of severely obese subjects (BMI e35 kg/m2) where very few clinical data are currently available.